Adrenergic drugs produce complex changes in ocular hydrodynamics which are mediated by interaction with different types of adrenoceptors. In the case of adrenergic agonists with strong alpha-adrenoceptor activity, the effect on intraocular pressure (IOP) can be biphasic; and early, transient rise in IOP followed by a long-lasting fall in IOP. In contrast, drugs with predominately beta-adrenoceptor activity produce a monophasic decline in IOP in normotensive and hypertensive eyes. The objective of this project is to elucidate the mode(s) by which adrenoceptors alter hydrodynamics in the eye and to correlate these effects with biochemical changes. Relatively selective beta-adrenoceptor agonists and antagonists will be used, alone and in combination, in three types of experiments: Study A: To evaluate the dose-response activities of beta-adrenergic agonists and antagonists in normotensive and hypertensive eyes of rabbits. Study B: To elucidate the nature of the beta-adrenoceptor primarily responsible for alteration in hydrodynamics. Study C: To determine changes in biochemical correlates (cyclic nucleotides, prostaglandins, amino acids, lactate, non-esterified free fatty acids) in aqueous humor during the action of beta-adrenoceptor agonists and antagonists. In summary, this project should provide: 1) a more complete understanding of the role of beta-adrenoceptors in modulating hydrodynamics and metabolism in the eye and 2) a more rational basis for the potential use of selective beta-adrenoceptor drugs in controlling glaucoma.